The invention relates to a heavy-current mercury low-pressure lamp with pressure equalisation space, wherein the anode and cathode electrodes are arranged one behind the other in a bulb and wherein the one of the two arms of the discharge space projects coaxially into the bulb and passes through the annular-shaped anode.
Lamps of this type are known from DE-OS 25 15 607 and are used preferably as ultra-violet radiation sources, e.g., for the sterilisation of foodstuffs. In the practical use of these lamps it has been discovered that is is possible for a direct arc-through to occur between cathode and anode through the pressure equalisation space, and that this possibly causes the destruction of the entire lamp. The cause of this arc-through lies in the unduly high temperature of the pressure equalisation space, the shape of which, in the known lamps, is determined substantially by two collar-shaped parts. The high temperature in the pressure compensation space of these lamps is the result of this space being heated by the radiation of the cathode. Heating also occurs by the anode column of the discharge.